title: Gonadal status-dependent effects of in vivo β-estradiol administration to female rats on in vitro epileptiform activity induced by low [Mg2+]₀ in combined hippocampus-entorhinal cortex slices.
abstract: There are controversial data regarding estrogen effects on neuronal excitability. We investigated whether β-estradiol (EB) administration to ovariectomized (OVX) or gonadally intact female rats alters epileptiform activity within the dentate gyrus network induced in vitro by removing [Mg2+]o in combined hippocampus-entorhinal cortex slices. In vivo EB administration significantly influenced the epileptiform activity in gonadal status-dependent manner. The onset of epileptiform discharges was modestly delayed in slices from OVX rats replaced with physiologically relevant doses of EB but the number of discharges was not affected. In contrast, EB administration to gonadally intact rats had robust effects such that: EB delayed the onset of discharges but significantly increased their number within the dentate gyrus network. Our data suggest that EB in physiologically relevant concentrations does not seem to negatively affect hippocampal neuronal excitability, nevertheless supraphysiological EB levels may enhance seizure severity.
authors.affiliation: Departments of Cell Biology & Anatomy, New York Medical College, Valhalla, NY, USA; Departments of Obstetrics & Gynecology, New York Medical College, Valhalla, NY, USA; Departments of Neurology, New York Medical College, Valhalla, NY, USA. Electronic address: jana_veliskova@nymc.edu.
authors.forename: Jana
authors.initials: J
authors.lastname: Velíšková
authors.forename: Libor
authors.initials: L
authors.lastname: Velíšek
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D018728:Entorhinal Cortex / Q000378:metabolism* / Q000503:physiopathology; D004827:Epilepsy / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology; D004958:Estradiol / Q000008:administration & dosage / Q000502:physiology*; D005260:Female; D006624:Hippocampus / Q000378:metabolism*; D008274:Magnesium / Q000009:adverse effects / Q000378:metabolism*; D009924:Organ Culture Techniques; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D012720:Severity of Illness Index; D016896:Treatment Outcome
chemical_list: D004958:Estradiol; D008274:Magnesium
keywords: Dentate gyrus network; Epileptiform discharges; Female rats; In vitro electrophysiology; Neuronal excitability; β-Estradiol